Is the burnt out Wayne Manor in Batman v Superman (based) on a real location/stately home or is it just a CGI model of a 'standard' stately home?
The burnt Wayne Manor in Batman v Superman: Dawn of Justice is based on a real location.
According to this article, Sutton Scarsdale Hall was used for the burnt Wayne Manor. The company 4DMax, which specializes in data capture for visual effects in movies, used three different kinds of scanners to collect points to map out a 3D model of the building's exterior. During Batman v Superman's post-production, this 3D model was added into the background as Wayne Manor.